/src/postgres/src/backend/optimizer/util/relnode.c

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/*-------------------------------------------------------------------------
 *
 * relnode.c
 *    Relation-node lookup/construction routines
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/optimizer/util/relnode.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <limits.h>

#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/inherit.h"
#include "optimizer/optimizer.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/placeholder.h"
#include "optimizer/plancat.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "parser/parse_relation.h"
#include "rewrite/rewriteManip.h"
#include "utils/hsearch.h"
#include "utils/lsyscache.h"


typedef struct JoinHashEntry
{
  Relids    join_relids;  /* hash key --- MUST BE FIRST */
  RelOptInfo *join_rel;
} JoinHashEntry;

static void build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel,
                RelOptInfo *input_rel,
                SpecialJoinInfo *sjinfo,
                List *pushed_down_joins,
                bool can_null);
static List *build_joinrel_restrictlist(PlannerInfo *root,
                    RelOptInfo *joinrel,
                    RelOptInfo *outer_rel,
                    RelOptInfo *inner_rel,
                    SpecialJoinInfo *sjinfo);
static void build_joinrel_joinlist(RelOptInfo *joinrel,
                   RelOptInfo *outer_rel,
                   RelOptInfo *inner_rel);
static List *subbuild_joinrel_restrictlist(PlannerInfo *root,
                       RelOptInfo *joinrel,
                       RelOptInfo *input_rel,
                       Relids both_input_relids,
                       List *new_restrictlist);
static List *subbuild_joinrel_joinlist(RelOptInfo *joinrel,
                     List *joininfo_list,
                     List *new_joininfo);
static void set_foreign_rel_properties(RelOptInfo *joinrel,
                     RelOptInfo *outer_rel, RelOptInfo *inner_rel);
static void add_join_rel(PlannerInfo *root, RelOptInfo *joinrel);
static void build_joinrel_partition_info(PlannerInfo *root,
                     RelOptInfo *joinrel,
                     RelOptInfo *outer_rel, RelOptInfo *inner_rel,
                     SpecialJoinInfo *sjinfo,
                     List *restrictlist);
static bool have_partkey_equi_join(PlannerInfo *root, RelOptInfo *joinrel,
                   RelOptInfo *rel1, RelOptInfo *rel2,
                   JoinType jointype, List *restrictlist);
static int  match_expr_to_partition_keys(Expr *expr, RelOptInfo *rel,
                     bool strict_op);
static void set_joinrel_partition_key_exprs(RelOptInfo *joinrel,
                      RelOptInfo *outer_rel, RelOptInfo *inner_rel,
                      JoinType jointype);
static void build_child_join_reltarget(PlannerInfo *root,
                     RelOptInfo *parentrel,
                     RelOptInfo *childrel,
                     int nappinfos,
                     AppendRelInfo **appinfos);


/*
 * setup_simple_rel_arrays
 *    Prepare the arrays we use for quickly accessing base relations
 *    and AppendRelInfos.
 */
void
setup_simple_rel_arrays(PlannerInfo *root)
{
  int     size;
  Index   rti;
  ListCell   *lc;

  /* Arrays are accessed using RT indexes (1..N) */
  size = list_length(root->parse->rtable) + 1;
  root->simple_rel_array_size = size;

  /*
   * simple_rel_array is initialized to all NULLs, since no RelOptInfos
   * exist yet.  It'll be filled by later calls to build_simple_rel().
   */
  root->simple_rel_array = (RelOptInfo **)
    palloc0(size * sizeof(RelOptInfo *));

  /* simple_rte_array is an array equivalent of the rtable list */
  root->simple_rte_array = (RangeTblEntry **)
    palloc0(size * sizeof(RangeTblEntry *));
  rti = 1;
  foreach(lc, root->parse->rtable)
  {
    RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);

    root->simple_rte_array[rti++] = rte;
  }

  /* append_rel_array is not needed if there are no AppendRelInfos */
  if (root->append_rel_list == NIL)
  {
    root->append_rel_array = NULL;
    return;
  }

  root->append_rel_array = (AppendRelInfo **)
    palloc0(size * sizeof(AppendRelInfo *));

  /*
   * append_rel_array is filled with any already-existing AppendRelInfos,
   * which currently could only come from UNION ALL flattening.  We might
   * add more later during inheritance expansion, but it's the
   * responsibility of the expansion code to update the array properly.
   */
  foreach(lc, root->append_rel_list)
  {
    AppendRelInfo *appinfo = lfirst_node(AppendRelInfo, lc);
    int     child_relid = appinfo->child_relid;

    /* Sanity check */
    Assert(child_relid < size);

    if (root->append_rel_array[child_relid])
      elog(ERROR, "child relation already exists");

    root->append_rel_array[child_relid] = appinfo;
  }
}

/*
 * expand_planner_arrays
 *    Expand the PlannerInfo's per-RTE arrays by add_size members
 *    and initialize the newly added entries to NULLs
 *
 * Note: this causes the append_rel_array to become allocated even if
 * it was not before.  This is okay for current uses, because we only call
 * this when adding child relations, which always have AppendRelInfos.
 */
void
expand_planner_arrays(PlannerInfo *root, int add_size)
{
  int     new_size;

  Assert(add_size > 0);

  new_size = root->simple_rel_array_size + add_size;

  root->simple_rel_array =
    repalloc0_array(root->simple_rel_array, RelOptInfo *, root->simple_rel_array_size, new_size);

  root->simple_rte_array =
    repalloc0_array(root->simple_rte_array, RangeTblEntry *, root->simple_rel_array_size, new_size);

  if (root->append_rel_array)
    root->append_rel_array =
      repalloc0_array(root->append_rel_array, AppendRelInfo *, root->simple_rel_array_size, new_size);
  else
    root->append_rel_array =
      palloc0_array(AppendRelInfo *, new_size);

  root->simple_rel_array_size = new_size;
}

/*
 * build_simple_rel
 *    Construct a new RelOptInfo for a base relation or 'other' relation.
 */
RelOptInfo *
build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
{
  RelOptInfo *rel;
  RangeTblEntry *rte;

  /* Rel should not exist already */
  Assert(relid > 0 && relid < root->simple_rel_array_size);
  if (root->simple_rel_array[relid] != NULL)
    elog(ERROR, "rel %d already exists", relid);

  /* Fetch RTE for relation */
  rte = root->simple_rte_array[relid];
  Assert(rte != NULL);

  rel = makeNode(RelOptInfo);
  rel->reloptkind = parent ? RELOPT_OTHER_MEMBER_REL : RELOPT_BASEREL;
  rel->relids = bms_make_singleton(relid);
  rel->rows = 0;
  /* cheap startup cost is interesting iff not all tuples to be retrieved */
  rel->consider_startup = (root->tuple_fraction > 0);
  rel->consider_param_startup = false;  /* might get changed later */
  rel->consider_parallel = false; /* might get changed later */
  rel->reltarget = create_empty_pathtarget();
  rel->pathlist = NIL;
  rel->ppilist = NIL;
  rel->partial_pathlist = NIL;
  rel->cheapest_startup_path = NULL;
  rel->cheapest_total_path = NULL;
  rel->cheapest_unique_path = NULL;
  rel->cheapest_parameterized_paths = NIL;
  rel->relid = relid;
  rel->rtekind = rte->rtekind;
  /* min_attr, max_attr, attr_needed, attr_widths are set below */
  rel->notnullattnums = NULL;
  rel->lateral_vars = NIL;
  rel->indexlist = NIL;
  rel->statlist = NIL;
  rel->pages = 0;
  rel->tuples = 0;
  rel->allvisfrac = 0;
  rel->eclass_indexes = NULL;
  rel->subroot = NULL;
  rel->subplan_params = NIL;
  rel->rel_parallel_workers = -1; /* set up in get_relation_info */
  rel->amflags = 0;
  rel->serverid = InvalidOid;
  if (rte->rtekind == RTE_RELATION)
  {
    Assert(parent == NULL ||
         parent->rtekind == RTE_RELATION ||
         parent->rtekind == RTE_SUBQUERY);

    /*
     * For any RELATION rte, we need a userid with which to check
     * permission access. Baserels simply use their own
     * RTEPermissionInfo's checkAsUser.
     *
     * For otherrels normally there's no RTEPermissionInfo, so we use the
     * parent's, which normally has one. The exceptional case is that the
     * parent is a subquery, in which case the otherrel will have its own.
     */
    if (rel->reloptkind == RELOPT_BASEREL ||
      (rel->reloptkind == RELOPT_OTHER_MEMBER_REL &&
       parent->rtekind == RTE_SUBQUERY))
    {
      RTEPermissionInfo *perminfo;

      perminfo = getRTEPermissionInfo(root->parse->rteperminfos, rte);
      rel->userid = perminfo->checkAsUser;
    }
    else
      rel->userid = parent->userid;
  }
  else
    rel->userid = InvalidOid;
  rel->useridiscurrent = false;
  rel->fdwroutine = NULL;
  rel->fdw_private = NULL;
  rel->unique_for_rels = NIL;
  rel->non_unique_for_rels = NIL;
  rel->baserestrictinfo = NIL;
  rel->baserestrictcost.startup = 0;
  rel->baserestrictcost.per_tuple = 0;
  rel->baserestrict_min_security = UINT_MAX;
  rel->joininfo = NIL;
  rel->has_eclass_joins = false;
  rel->consider_partitionwise_join = false; /* might get changed later */
  rel->part_scheme = NULL;
  rel->nparts = -1;
  rel->boundinfo = NULL;
  rel->partbounds_merged = false;
  rel->partition_qual = NIL;
  rel->part_rels = NULL;
  rel->live_parts = NULL;
  rel->all_partrels = NULL;
  rel->partexprs = NULL;
  rel->nullable_partexprs = NULL;

  /*
   * Pass assorted information down the inheritance hierarchy.
   */
  if (parent)
  {
    /* We keep back-links to immediate parent and topmost parent. */
    rel->parent = parent;
    rel->top_parent = parent->top_parent ? parent->top_parent : parent;
    rel->top_parent_relids = rel->top_parent->relids;

    /*
     * A child rel is below the same outer joins as its parent.  (We
     * presume this info was already calculated for the parent.)
     */
    rel->nulling_relids = parent->nulling_relids;

    /*
     * Also propagate lateral-reference information from appendrel parent
     * rels to their child rels.  We intentionally give each child rel the
     * same minimum parameterization, even though it's quite possible that
     * some don't reference all the lateral rels.  This is because any
     * append path for the parent will have to have the same
     * parameterization for every child anyway, and there's no value in
     * forcing extra reparameterize_path() calls.  Similarly, a lateral
     * reference to the parent prevents use of otherwise-movable join rels
     * for each child.
     *
     * It's possible for child rels to have their own children, in which
     * case the topmost parent's lateral info propagates all the way down.
     */
    rel->direct_lateral_relids = parent->direct_lateral_relids;
    rel->lateral_relids = parent->lateral_relids;
    rel->lateral_referencers = parent->lateral_referencers;
  }
  else
  {
    rel->parent = NULL;
    rel->top_parent = NULL;
    rel->top_parent_relids = NULL;
    rel->nulling_relids = NULL;
    rel->direct_lateral_relids = NULL;
    rel->lateral_relids = NULL;
    rel->lateral_referencers = NULL;
  }

  /* Check type of rtable entry */
  switch (rte->rtekind)
  {
    case RTE_RELATION:
      /* Table --- retrieve statistics from the system catalogs */
      get_relation_info(root, rte->relid, rte->inh, rel);
      break;
    case RTE_SUBQUERY:
    case RTE_FUNCTION:
    case RTE_TABLEFUNC:
    case RTE_VALUES:
    case RTE_CTE:
    case RTE_NAMEDTUPLESTORE:

      /*
       * Subquery, function, tablefunc, values list, CTE, or ENR --- set
       * up attr range and arrays
       *
       * Note: 0 is included in range to support whole-row Vars
       */
      rel->min_attr = 0;
      rel->max_attr = list_length(rte->eref->colnames);
      rel->attr_needed = (Relids *)
        palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(Relids));
      rel->attr_widths = (int32 *)
        palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(int32));
      break;
    case RTE_RESULT:
      /* RTE_RESULT has no columns, nor could it have whole-row Var */
      rel->min_attr = 0;
      rel->max_attr = -1;
      rel->attr_needed = NULL;
      rel->attr_widths = NULL;
      break;
    default:
      elog(ERROR, "unrecognized RTE kind: %d",
         (int) rte->rtekind);
      break;
  }

  /*
   * We must apply the partially filled in RelOptInfo before calling
   * apply_child_basequals due to some transformations within that function
   * which require the RelOptInfo to be available in the simple_rel_array.
   */
  root->simple_rel_array[relid] = rel;

  /*
   * Apply the parent's quals to the child, with appropriate substitution of
   * variables.  If the resulting clause is constant-FALSE or NULL after
   * applying transformations, apply_child_basequals returns false to
   * indicate that scanning this relation won't yield any rows.  In this
   * case, we mark the child as dummy right away.  (We must do this
   * immediately so that pruning works correctly when recursing in
   * expand_partitioned_rtentry.)
   */
  if (parent)
  {
    AppendRelInfo *appinfo = root->append_rel_array[relid];

    Assert(appinfo != NULL);
    if (!apply_child_basequals(root, parent, rel, rte, appinfo))
    {
      /*
       * Restriction clause reduced to constant FALSE or NULL.  Mark as
       * dummy so we won't scan this relation.
       */
      mark_dummy_rel(rel);
    }
  }

  return rel;
}

/*
 * find_base_rel
 *    Find a base or otherrel relation entry, which must already exist.
 */
RelOptInfo *
find_base_rel(PlannerInfo *root, int relid)
{
  RelOptInfo *rel;

  /* use an unsigned comparison to prevent negative array element access */
  if ((uint32) relid < (uint32) root->simple_rel_array_size)
  {
    rel = root->simple_rel_array[relid];
    if (rel)
      return rel;
  }

  elog(ERROR, "no relation entry for relid %d", relid);

  return NULL;       /* keep compiler quiet */
}

/*
 * find_base_rel_noerr
 *    Find a base or otherrel relation entry, returning NULL if there's none
 */
RelOptInfo *
find_base_rel_noerr(PlannerInfo *root, int relid)
{
  /* use an unsigned comparison to prevent negative array element access */
  if ((uint32) relid < (uint32) root->simple_rel_array_size)
    return root->simple_rel_array[relid];
  return NULL;
}

/*
 * find_base_rel_ignore_join
 *    Find a base or otherrel relation entry, which must already exist.
 *
 * Unlike find_base_rel, if relid references an outer join then this
 * will return NULL rather than raising an error.  This is convenient
 * for callers that must deal with relid sets including both base and
 * outer joins.
 */
RelOptInfo *
find_base_rel_ignore_join(PlannerInfo *root, int relid)
{
  /* use an unsigned comparison to prevent negative array element access */
  if ((uint32) relid < (uint32) root->simple_rel_array_size)
  {
    RelOptInfo *rel;
    RangeTblEntry *rte;

    rel = root->simple_rel_array[relid];
    if (rel)
      return rel;

    /*
     * We could just return NULL here, but for debugging purposes it seems
     * best to actually verify that the relid is an outer join and not
     * something weird.
     */
    rte = root->simple_rte_array[relid];
    if (rte && rte->rtekind == RTE_JOIN && rte->jointype != JOIN_INNER)
      return NULL;
  }

  elog(ERROR, "no relation entry for relid %d", relid);

  return NULL;       /* keep compiler quiet */
}

/*
 * build_join_rel_hash
 *    Construct the auxiliary hash table for join relations.
 */
static void
build_join_rel_hash(PlannerInfo *root)
{
  HTAB     *hashtab;
  HASHCTL   hash_ctl;
  ListCell   *l;

  /* Create the hash table */
  hash_ctl.keysize = sizeof(Relids);
  hash_ctl.entrysize = sizeof(JoinHashEntry);
  hash_ctl.hash = bitmap_hash;
  hash_ctl.match = bitmap_match;
  hash_ctl.hcxt = CurrentMemoryContext;
  hashtab = hash_create("JoinRelHashTable",
              256L,
              &hash_ctl,
              HASH_ELEM | HASH_FUNCTION | HASH_COMPARE | HASH_CONTEXT);

  /* Insert all the already-existing joinrels */
  foreach(l, root->join_rel_list)
  {
    RelOptInfo *rel = (RelOptInfo *) lfirst(l);
    JoinHashEntry *hentry;
    bool    found;

    hentry = (JoinHashEntry *) hash_search(hashtab,
                         &(rel->relids),
                         HASH_ENTER,
                         &found);
    Assert(!found);
    hentry->join_rel = rel;
  }

  root->join_rel_hash = hashtab;
}

/*
 * find_join_rel
 *    Returns relation entry corresponding to 'relids' (a set of RT indexes),
 *    or NULL if none exists.  This is for join relations.
 */
RelOptInfo *
find_join_rel(PlannerInfo *root, Relids relids)
{
  /*
   * Switch to using hash lookup when list grows "too long".  The threshold
   * is arbitrary and is known only here.
   */
  if (!root->join_rel_hash && list_length(root->join_rel_list) > 32)
    build_join_rel_hash(root);

  /*
   * Use either hashtable lookup or linear search, as appropriate.
   *
   * Note: the seemingly redundant hashkey variable is used to avoid taking
   * the address of relids; unless the compiler is exceedingly smart, doing
   * so would force relids out of a register and thus probably slow down the
   * list-search case.
   */
  if (root->join_rel_hash)
  {
    Relids    hashkey = relids;
    JoinHashEntry *hentry;

    hentry = (JoinHashEntry *) hash_search(root->join_rel_hash,
                         &hashkey,
                         HASH_FIND,
                         NULL);
    if (hentry)
      return hentry->join_rel;
  }
  else
  {
    ListCell   *l;

    foreach(l, root->join_rel_list)
    {
      RelOptInfo *rel = (RelOptInfo *) lfirst(l);

      if (bms_equal(rel->relids, relids))
        return rel;
    }
  }

  return NULL;
}

/*
 * set_foreign_rel_properties
 *    Set up foreign-join fields if outer and inner relation are foreign
 *    tables (or joins) belonging to the same server and assigned to the same
 *    user to check access permissions as.
 *
 * In addition to an exact match of userid, we allow the case where one side
 * has zero userid (implying current user) and the other side has explicit
 * userid that happens to equal the current user; but in that case, pushdown of
 * the join is only valid for the current user.  The useridiscurrent field
 * records whether we had to make such an assumption for this join or any
 * sub-join.
 *
 * Otherwise these fields are left invalid, so GetForeignJoinPaths will not be
 * called for the join relation.
 */
static void
set_foreign_rel_properties(RelOptInfo *joinrel, RelOptInfo *outer_rel,
               RelOptInfo *inner_rel)
{
  if (OidIsValid(outer_rel->serverid) &&
    inner_rel->serverid == outer_rel->serverid)
  {
    if (inner_rel->userid == outer_rel->userid)
    {
      joinrel->serverid = outer_rel->serverid;
      joinrel->userid = outer_rel->userid;
      joinrel->useridiscurrent = outer_rel->useridiscurrent || inner_rel->useridiscurrent;
      joinrel->fdwroutine = outer_rel->fdwroutine;
    }
    else if (!OidIsValid(inner_rel->userid) &&
         outer_rel->userid == GetUserId())
    {
      joinrel->serverid = outer_rel->serverid;
      joinrel->userid = outer_rel->userid;
      joinrel->useridiscurrent = true;
      joinrel->fdwroutine = outer_rel->fdwroutine;
    }
    else if (!OidIsValid(outer_rel->userid) &&
         inner_rel->userid == GetUserId())
    {
      joinrel->serverid = outer_rel->serverid;
      joinrel->userid = inner_rel->userid;
      joinrel->useridiscurrent = true;
      joinrel->fdwroutine = outer_rel->fdwroutine;
    }
  }
}

/*
 * add_join_rel
 *    Add given join relation to the list of join relations in the given
 *    PlannerInfo. Also add it to the auxiliary hashtable if there is one.
 */
static void
add_join_rel(PlannerInfo *root, RelOptInfo *joinrel)
{
  /* GEQO requires us to append the new joinrel to the end of the list! */
  root->join_rel_list = lappend(root->join_rel_list, joinrel);

  /* store it into the auxiliary hashtable if there is one. */
  if (root->join_rel_hash)
  {
    JoinHashEntry *hentry;
    bool    found;

    hentry = (JoinHashEntry *) hash_search(root->join_rel_hash,
                         &(joinrel->relids),
                         HASH_ENTER,
                         &found);
    Assert(!found);
    hentry->join_rel = joinrel;
  }
}

/*
 * build_join_rel
 *    Returns relation entry corresponding to the union of two given rels,
 *    creating a new relation entry if none already exists.
 *
 * 'joinrelids' is the Relids set that uniquely identifies the join
 * 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
 *    joined
 * 'sjinfo': join context info
 * 'pushed_down_joins': any pushed-down outer joins that are now completed
 * 'restrictlist_ptr': result variable.  If not NULL, *restrictlist_ptr
 *    receives the list of RestrictInfo nodes that apply to this
 *    particular pair of joinable relations.
 *
 * restrictlist_ptr makes the routine's API a little grotty, but it saves
 * duplicated calculation of the restrictlist...
 */
RelOptInfo *
build_join_rel(PlannerInfo *root,
         Relids joinrelids,
         RelOptInfo *outer_rel,
         RelOptInfo *inner_rel,
         SpecialJoinInfo *sjinfo,
         List *pushed_down_joins,
         List **restrictlist_ptr)
{
  RelOptInfo *joinrel;
  List     *restrictlist;

  /* This function should be used only for join between parents. */
  Assert(!IS_OTHER_REL(outer_rel) && !IS_OTHER_REL(inner_rel));

  /*
   * See if we already have a joinrel for this set of base rels.
   */
  joinrel = find_join_rel(root, joinrelids);

  if (joinrel)
  {
    /*
     * Yes, so we only need to figure the restrictlist for this particular
     * pair of component relations.
     */
    if (restrictlist_ptr)
      *restrictlist_ptr = build_joinrel_restrictlist(root,
                               joinrel,
                               outer_rel,
                               inner_rel,
                               sjinfo);
    return joinrel;
  }

  /*
   * Nope, so make one.
   */
  joinrel = makeNode(RelOptInfo);
  joinrel->reloptkind = RELOPT_JOINREL;
  joinrel->relids = bms_copy(joinrelids);
  joinrel->rows = 0;
  /* cheap startup cost is interesting iff not all tuples to be retrieved */
  joinrel->consider_startup = (root->tuple_fraction > 0);
  joinrel->consider_param_startup = false;
  joinrel->consider_parallel = false;
  joinrel->reltarget = create_empty_pathtarget();
  joinrel->pathlist = NIL;
  joinrel->ppilist = NIL;
  joinrel->partial_pathlist = NIL;
  joinrel->cheapest_startup_path = NULL;
  joinrel->cheapest_total_path = NULL;
  joinrel->cheapest_unique_path = NULL;
  joinrel->cheapest_parameterized_paths = NIL;
  /* init direct_lateral_relids from children; we'll finish it up below */
  joinrel->direct_lateral_relids =
    bms_union(outer_rel->direct_lateral_relids,
          inner_rel->direct_lateral_relids);
  joinrel->lateral_relids = min_join_parameterization(root, joinrel->relids,
                            outer_rel, inner_rel);
  joinrel->relid = 0;     /* indicates not a baserel */
  joinrel->rtekind = RTE_JOIN;
  joinrel->min_attr = 0;
  joinrel->max_attr = 0;
  joinrel->attr_needed = NULL;
  joinrel->attr_widths = NULL;
  joinrel->notnullattnums = NULL;
  joinrel->nulling_relids = NULL;
  joinrel->lateral_vars = NIL;
  joinrel->lateral_referencers = NULL;
  joinrel->indexlist = NIL;
  joinrel->statlist = NIL;
  joinrel->pages = 0;
  joinrel->tuples = 0;
  joinrel->allvisfrac = 0;
  joinrel->eclass_indexes = NULL;
  joinrel->subroot = NULL;
  joinrel->subplan_params = NIL;
  joinrel->rel_parallel_workers = -1;
  joinrel->amflags = 0;
  joinrel->serverid = InvalidOid;
  joinrel->userid = InvalidOid;
  joinrel->useridiscurrent = false;
  joinrel->fdwroutine = NULL;
  joinrel->fdw_private = NULL;
  joinrel->unique_for_rels = NIL;
  joinrel->non_unique_for_rels = NIL;
  joinrel->baserestrictinfo = NIL;
  joinrel->baserestrictcost.startup = 0;
  joinrel->baserestrictcost.per_tuple = 0;
  joinrel->baserestrict_min_security = UINT_MAX;
  joinrel->joininfo = NIL;
  joinrel->has_eclass_joins = false;
  joinrel->consider_partitionwise_join = false; /* might get changed later */
  joinrel->parent = NULL;
  joinrel->top_parent = NULL;
  joinrel->top_parent_relids = NULL;
  joinrel->part_scheme = NULL;
  joinrel->nparts = -1;
  joinrel->boundinfo = NULL;
  joinrel->partbounds_merged = false;
  joinrel->partition_qual = NIL;
  joinrel->part_rels = NULL;
  joinrel->live_parts = NULL;
  joinrel->all_partrels = NULL;
  joinrel->partexprs = NULL;
  joinrel->nullable_partexprs = NULL;

  /* Compute information relevant to the foreign relations. */
  set_foreign_rel_properties(joinrel, outer_rel, inner_rel);

  /*
   * Fill the joinrel's tlist with just the Vars and PHVs that need to be
   * output from this join (ie, are needed for higher joinclauses or final
   * output).
   *
   * NOTE: the tlist order for a join rel will depend on which pair of outer
   * and inner rels we first try to build it from.  But the contents should
   * be the same regardless.
   */
  build_joinrel_tlist(root, joinrel, outer_rel, sjinfo, pushed_down_joins,
            (sjinfo->jointype == JOIN_FULL));
  build_joinrel_tlist(root, joinrel, inner_rel, sjinfo, pushed_down_joins,
            (sjinfo->jointype != JOIN_INNER));
  add_placeholders_to_joinrel(root, joinrel, outer_rel, inner_rel, sjinfo);

  /*
   * add_placeholders_to_joinrel also took care of adding the ph_lateral
   * sets of any PlaceHolderVars computed here to direct_lateral_relids, so
   * now we can finish computing that.  This is much like the computation of
   * the transitively-closed lateral_relids in min_join_parameterization,
   * except that here we *do* have to consider the added PHVs.
   */
  joinrel->direct_lateral_relids =
    bms_del_members(joinrel->direct_lateral_relids, joinrel->relids);

  /*
   * Construct restrict and join clause lists for the new joinrel. (The
   * caller might or might not need the restrictlist, but I need it anyway
   * for set_joinrel_size_estimates().)
   */
  restrictlist = build_joinrel_restrictlist(root, joinrel,
                        outer_rel, inner_rel,
                        sjinfo);
  if (restrictlist_ptr)
    *restrictlist_ptr = restrictlist;
  build_joinrel_joinlist(joinrel, outer_rel, inner_rel);

  /*
   * This is also the right place to check whether the joinrel has any
   * pending EquivalenceClass joins.
   */
  joinrel->has_eclass_joins = has_relevant_eclass_joinclause(root, joinrel);

  /* Store the partition information. */
  build_joinrel_partition_info(root, joinrel, outer_rel, inner_rel, sjinfo,
                 restrictlist);

  /*
   * Set estimates of the joinrel's size.
   */
  set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel,
                 sjinfo, restrictlist);

  /*
   * Set the consider_parallel flag if this joinrel could potentially be
   * scanned within a parallel worker.  If this flag is false for either
   * inner_rel or outer_rel, then it must be false for the joinrel also.
   * Even if both are true, there might be parallel-restricted expressions
   * in the targetlist or quals.
   *
   * Note that if there are more than two rels in this relation, they could
   * be divided between inner_rel and outer_rel in any arbitrary way.  We
   * assume this doesn't matter, because we should hit all the same baserels
   * and joinclauses while building up to this joinrel no matter which we
   * take; therefore, we should make the same decision here however we get
   * here.
   */
  if (inner_rel->consider_parallel && outer_rel->consider_parallel &&
    is_parallel_safe(root, (Node *) restrictlist) &&
    is_parallel_safe(root, (Node *) joinrel->reltarget->exprs))
    joinrel->consider_parallel = true;

  /* Add the joinrel to the PlannerInfo. */
  add_join_rel(root, joinrel);

  /*
   * Also, if dynamic-programming join search is active, add the new joinrel
   * to the appropriate sublist.  Note: you might think the Assert on number
   * of members should be for equality, but some of the level 1 rels might
   * have been joinrels already, so we can only assert <=.
   */
  if (root->join_rel_level)
  {
    Assert(root->join_cur_level > 0);
    Assert(root->join_cur_level <= bms_num_members(joinrel->relids));
    root->join_rel_level[root->join_cur_level] =
      lappend(root->join_rel_level[root->join_cur_level], joinrel);
  }

  return joinrel;
}

/*
 * build_child_join_rel
 *    Builds RelOptInfo representing join between given two child relations.
 *
 * 'outer_rel' and 'inner_rel' are the RelOptInfos of child relations being
 *    joined
 * 'parent_joinrel' is the RelOptInfo representing the join between parent
 *    relations. Some of the members of new RelOptInfo are produced by
 *    translating corresponding members of this RelOptInfo
 * 'restrictlist': list of RestrictInfo nodes that apply to this particular
 *    pair of joinable relations
 * 'sjinfo': child join's join-type details
 * 'nappinfos' and 'appinfos': AppendRelInfo array for child relids
 */
RelOptInfo *
build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,
           RelOptInfo *inner_rel, RelOptInfo *parent_joinrel,
           List *restrictlist, SpecialJoinInfo *sjinfo,
           int nappinfos, AppendRelInfo **appinfos)
{
  RelOptInfo *joinrel = makeNode(RelOptInfo);

  /* Only joins between "other" relations land here. */
  Assert(IS_OTHER_REL(outer_rel) && IS_OTHER_REL(inner_rel));

  /* The parent joinrel should have consider_partitionwise_join set. */
  Assert(parent_joinrel->consider_partitionwise_join);

  joinrel->reloptkind = RELOPT_OTHER_JOINREL;
  joinrel->relids = adjust_child_relids(parent_joinrel->relids,
                      nappinfos, appinfos);
  joinrel->rows = 0;
  /* cheap startup cost is interesting iff not all tuples to be retrieved */
  joinrel->consider_startup = (root->tuple_fraction > 0);
  joinrel->consider_param_startup = false;
  joinrel->consider_parallel = false;
  joinrel->reltarget = create_empty_pathtarget();
  joinrel->pathlist = NIL;
  joinrel->ppilist = NIL;
  joinrel->partial_pathlist = NIL;
  joinrel->cheapest_startup_path = NULL;
  joinrel->cheapest_total_path = NULL;
  joinrel->cheapest_unique_path = NULL;
  joinrel->cheapest_parameterized_paths = NIL;
  joinrel->direct_lateral_relids = NULL;
  joinrel->lateral_relids = NULL;
  joinrel->relid = 0;     /* indicates not a baserel */
  joinrel->rtekind = RTE_JOIN;
  joinrel->min_attr = 0;
  joinrel->max_attr = 0;
  joinrel->attr_needed = NULL;
  joinrel->attr_widths = NULL;
  joinrel->notnullattnums = NULL;
  joinrel->nulling_relids = NULL;
  joinrel->lateral_vars = NIL;
  joinrel->lateral_referencers = NULL;
  joinrel->indexlist = NIL;
  joinrel->pages = 0;
  joinrel->tuples = 0;
  joinrel->allvisfrac = 0;
  joinrel->eclass_indexes = NULL;
  joinrel->subroot = NULL;
  joinrel->subplan_params = NIL;
  joinrel->amflags = 0;
  joinrel->serverid = InvalidOid;
  joinrel->userid = InvalidOid;
  joinrel->useridiscurrent = false;
  joinrel->fdwroutine = NULL;
  joinrel->fdw_private = NULL;
  joinrel->baserestrictinfo = NIL;
  joinrel->baserestrictcost.startup = 0;
  joinrel->baserestrictcost.per_tuple = 0;
  joinrel->joininfo = NIL;
  joinrel->has_eclass_joins = false;
  joinrel->consider_partitionwise_join = false; /* might get changed later */
  joinrel->parent = parent_joinrel;
  joinrel->top_parent = parent_joinrel->top_parent ? parent_joinrel->top_parent : parent_joinrel;
  joinrel->top_parent_relids = joinrel->top_parent->relids;
  joinrel->part_scheme = NULL;
  joinrel->nparts = -1;
  joinrel->boundinfo = NULL;
  joinrel->partbounds_merged = false;
  joinrel->partition_qual = NIL;
  joinrel->part_rels = NULL;
  joinrel->live_parts = NULL;
  joinrel->all_partrels = NULL;
  joinrel->partexprs = NULL;
  joinrel->nullable_partexprs = NULL;

  /* Compute information relevant to foreign relations. */
  set_foreign_rel_properties(joinrel, outer_rel, inner_rel);

  /* Set up reltarget struct */
  build_child_join_reltarget(root, parent_joinrel, joinrel,
                 nappinfos, appinfos);

  /* Construct joininfo list. */
  joinrel->joininfo = (List *) adjust_appendrel_attrs(root,
                            (Node *) parent_joinrel->joininfo,
                            nappinfos,
                            appinfos);

  /*
   * Lateral relids referred in child join will be same as that referred in
   * the parent relation.
   */
  joinrel->direct_lateral_relids = (Relids) bms_copy(parent_joinrel->direct_lateral_relids);
  joinrel->lateral_relids = (Relids) bms_copy(parent_joinrel->lateral_relids);

  /*
   * If the parent joinrel has pending equivalence classes, so does the
   * child.
   */
  joinrel->has_eclass_joins = parent_joinrel->has_eclass_joins;

  /* Is the join between partitions itself partitioned? */
  build_joinrel_partition_info(root, joinrel, outer_rel, inner_rel, sjinfo,
                 restrictlist);

  /* Child joinrel is parallel safe if parent is parallel safe. */
  joinrel->consider_parallel = parent_joinrel->consider_parallel;

  /* Set estimates of the child-joinrel's size. */
  set_joinrel_size_estimates(root, joinrel, outer_rel, inner_rel,
                 sjinfo, restrictlist);

  /* We build the join only once. */
  Assert(!find_join_rel(root, joinrel->relids));

  /* Add the relation to the PlannerInfo. */
  add_join_rel(root, joinrel);

  /*
   * We might need EquivalenceClass members corresponding to the child join,
   * so that we can represent sort pathkeys for it.  As with children of
   * baserels, we shouldn't need this unless there are relevant eclass joins
   * (implying that a merge join might be possible) or pathkeys to sort by.
   */
  if (joinrel->has_eclass_joins || has_useful_pathkeys(root, parent_joinrel))
    add_child_join_rel_equivalences(root,
                    nappinfos, appinfos,
                    parent_joinrel, joinrel);

  return joinrel;
}

/*
 * min_join_parameterization
 *
 * Determine the minimum possible parameterization of a joinrel, that is, the
 * set of other rels it contains LATERAL references to.  We save this value in
 * the join's RelOptInfo.  This function is split out of build_join_rel()
 * because join_is_legal() needs the value to check a prospective join.
 */
Relids
min_join_parameterization(PlannerInfo *root,
              Relids joinrelids,
              RelOptInfo *outer_rel,
              RelOptInfo *inner_rel)
{
  Relids    result;

  /*
   * Basically we just need the union of the inputs' lateral_relids, less
   * whatever is already in the join.
   *
   * It's not immediately obvious that this is a valid way to compute the
   * result, because it might seem that we're ignoring possible lateral refs
   * of PlaceHolderVars that are due to be computed at the join but not in
   * either input.  However, because create_lateral_join_info() already
   * charged all such PHV refs to each member baserel of the join, they'll
   * be accounted for already in the inputs' lateral_relids.  Likewise, we
   * do not need to worry about doing transitive closure here, because that
   * was already accounted for in the original baserel lateral_relids.
   */
  result = bms_union(outer_rel->lateral_relids, inner_rel->lateral_relids);
  result = bms_del_members(result, joinrelids);
  return result;
}

/*
 * build_joinrel_tlist
 *    Builds a join relation's target list from an input relation.
 *    (This is invoked twice to handle the two input relations.)
 *
 * The join's targetlist includes all Vars of its member relations that
 * will still be needed above the join.  This subroutine adds all such
 * Vars from the specified input rel's tlist to the join rel's tlist.
 * Likewise for any PlaceHolderVars emitted by the input rel.
 *
 * We also compute the expected width of the join's output, making use
 * of data that was cached at the baserel level by set_rel_width().
 *
 * Pass can_null as true if the join is an outer join that can null Vars
 * from this input relation.  If so, we will (normally) add the join's relid
 * to the nulling bitmaps of Vars and PHVs bubbled up from the input.
 *
 * When forming an outer join's target list, special handling is needed in
 * case the outer join was commuted with another one per outer join identity 3
 * (see optimizer/README).  We must take steps to ensure that the output Vars
 * have the same nulling bitmaps that they would if the two joins had been
 * done in syntactic order; else they won't match Vars appearing higher in
 * the query tree.  An exception to the match-the-syntactic-order rule is
 * that when an outer join is pushed down into another one's RHS per identity
 * 3, we can't mark its Vars as nulled until the now-upper outer join is also
 * completed.  So we need to do three things:
 *
 * First, we add the outer join's relid to the nulling bitmap only if the
 * outer join has been completely performed and the Var or PHV actually
 * comes from within the syntactically nullable side(s) of the outer join.
 * This takes care of the possibility that we have transformed
 *    (A leftjoin B on (Pab)) leftjoin C on (Pbc)
 * to
 *    A leftjoin (B leftjoin C on (Pbc)) on (Pab)
 * Here the pushed-down B/C join cannot mark C columns as nulled yet,
 * while the now-upper A/B join must not mark C columns as nulled by itself.
 *
 * Second, perform the same operation for each SpecialJoinInfo listed in
 * pushed_down_joins (which, in this example, would be the B/C join when
 * we are at the now-upper A/B join).  This allows the now-upper join to
 * complete the marking of "C" Vars that now have fully valid values.
 *
 * Third, any relid in sjinfo->commute_above_r that is already part of
 * the joinrel is added to the nulling bitmaps of nullable Vars and PHVs.
 * This takes care of the reverse case where we implement
 *    A leftjoin (B leftjoin C on (Pbc)) on (Pab)
 * as
 *    (A leftjoin B on (Pab)) leftjoin C on (Pbc)
 * The C columns emitted by the B/C join need to be shown as nulled by both
 * the B/C and A/B joins, even though they've not physically traversed the
 * A/B join.
 */
static void
build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel,
          RelOptInfo *input_rel,
          SpecialJoinInfo *sjinfo,
          List *pushed_down_joins,
          bool can_null)
{
  Relids    relids = joinrel->relids;
  int64   tuple_width = joinrel->reltarget->width;
  ListCell   *vars;
  ListCell   *lc;

  foreach(vars, input_rel->reltarget->exprs)
  {
    Var      *var = (Var *) lfirst(vars);

    /*
     * For a PlaceHolderVar, we have to look up the PlaceHolderInfo.
     */
    if (IsA(var, PlaceHolderVar))
    {
      PlaceHolderVar *phv = (PlaceHolderVar *) var;
      PlaceHolderInfo *phinfo = find_placeholder_info(root, phv);

      /* Is it still needed above this joinrel? */
      if (bms_nonempty_difference(phinfo->ph_needed, relids))
      {
        /*
         * Yup, add it to the output.  If this join potentially nulls
         * this input, we have to update the PHV's phnullingrels,
         * which means making a copy.
         */
        if (can_null)
        {
          phv = copyObject(phv);
          /* See comments above to understand this logic */
          if (sjinfo->ojrelid != 0 &&
            bms_is_member(sjinfo->ojrelid, relids) &&
            (bms_is_subset(phv->phrels, sjinfo->syn_righthand) ||
             (sjinfo->jointype == JOIN_FULL &&
              bms_is_subset(phv->phrels, sjinfo->syn_lefthand))))
            phv->phnullingrels = bms_add_member(phv->phnullingrels,
                              sjinfo->ojrelid);
          foreach(lc, pushed_down_joins)
          {
            SpecialJoinInfo *othersj = (SpecialJoinInfo *) lfirst(lc);

            Assert(bms_is_member(othersj->ojrelid, relids));
            if (bms_is_subset(phv->phrels, othersj->syn_righthand))
              phv->phnullingrels = bms_add_member(phv->phnullingrels,
                                othersj->ojrelid);
          }
          phv->phnullingrels =
            bms_join(phv->phnullingrels,
                 bms_intersect(sjinfo->commute_above_r,
                         relids));
        }

        joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs,
                          phv);
        /* Bubbling up the precomputed result has cost zero */
        tuple_width += phinfo->ph_width;
      }
      continue;
    }

    /*
     * Otherwise, anything in a baserel or joinrel targetlist ought to be
     * a Var.  (More general cases can only appear in appendrel child
     * rels, which will never be seen here.)
     */
    if (!IsA(var, Var))
      elog(ERROR, "unexpected node type in rel targetlist: %d",
         (int) nodeTag(var));

    if (var->varno == ROWID_VAR)
    {
      /* UPDATE/DELETE/MERGE row identity vars are always needed */
      RowIdentityVarInfo *ridinfo = (RowIdentityVarInfo *)
        list_nth(root->row_identity_vars, var->varattno - 1);

      /* Update reltarget width estimate from RowIdentityVarInfo */
      tuple_width += ridinfo->rowidwidth;
    }
    else
    {
      RelOptInfo *baserel;
      int     ndx;

      /* Get the Var's original base rel */
      baserel = find_base_rel(root, var->varno);

      /* Is it still needed above this joinrel? */
      ndx = var->varattno - baserel->min_attr;
      if (!bms_nonempty_difference(baserel->attr_needed[ndx], relids))
        continue;   /* nope, skip it */

      /* Update reltarget width estimate from baserel's attr_widths */
      tuple_width += baserel->attr_widths[ndx];
    }

    /*
     * Add the Var to the output.  If this join potentially nulls this
     * input, we have to update the Var's varnullingrels, which means
     * making a copy.  But note that we don't ever add nullingrel bits to
     * row identity Vars (cf. comments in setrefs.c).
     */
    if (can_null && var->varno != ROWID_VAR)
    {
      var = copyObject(var);
      /* See comments above to understand this logic */
      if (sjinfo->ojrelid != 0 &&
        bms_is_member(sjinfo->ojrelid, relids) &&
        (bms_is_member(var->varno, sjinfo->syn_righthand) ||
         (sjinfo->jointype == JOIN_FULL &&
          bms_is_member(var->varno, sjinfo->syn_lefthand))))
        var->varnullingrels = bms_add_member(var->varnullingrels,
                           sjinfo->ojrelid);
      foreach(lc, pushed_down_joins)
      {
        SpecialJoinInfo *othersj = (SpecialJoinInfo *) lfirst(lc);

        Assert(bms_is_member(othersj->ojrelid, relids));
        if (bms_is_member(var->varno, othersj->syn_righthand))
          var->varnullingrels = bms_add_member(var->varnullingrels,
                             othersj->ojrelid);
      }
      var->varnullingrels =
        bms_join(var->varnullingrels,
             bms_intersect(sjinfo->commute_above_r,
                     relids));
    }

    joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs,
                      var);

    /* Vars have cost zero, so no need to adjust reltarget->cost */
  }

  joinrel->reltarget->width = clamp_width_est(tuple_width);
}

/*
 * build_joinrel_restrictlist
 * build_joinrel_joinlist
 *    These routines build lists of restriction and join clauses for a
 *    join relation from the joininfo lists of the relations it joins.
 *
 *    These routines are separate because the restriction list must be
 *    built afresh for each pair of input sub-relations we consider, whereas
 *    the join list need only be computed once for any join RelOptInfo.
 *    The join list is fully determined by the set of rels making up the
 *    joinrel, so we should get the same results (up to ordering) from any
 *    candidate pair of sub-relations.  But the restriction list is whatever
 *    is not handled in the sub-relations, so it depends on which
 *    sub-relations are considered.
 *
 *    If a join clause from an input relation refers to base+OJ rels still not
 *    present in the joinrel, then it is still a join clause for the joinrel;
 *    we put it into the joininfo list for the joinrel.  Otherwise,
 *    the clause is now a restrict clause for the joined relation, and we
 *    return it to the caller of build_joinrel_restrictlist() to be stored in
 *    join paths made from this pair of sub-relations.  (It will not need to
 *    be considered further up the join tree.)
 *
 *    In many cases we will find the same RestrictInfos in both input
 *    relations' joinlists, so be careful to eliminate duplicates.
 *    Pointer equality should be a sufficient test for dups, since all
 *    the various joinlist entries ultimately refer to RestrictInfos
 *    pushed into them by distribute_restrictinfo_to_rels().
 *
 * 'joinrel' is a join relation node
 * 'outer_rel' and 'inner_rel' are a pair of relations that can be joined
 *    to form joinrel.
 * 'sjinfo': join context info
 *
 * build_joinrel_restrictlist() returns a list of relevant restrictinfos,
 * whereas build_joinrel_joinlist() stores its results in the joinrel's
 * joininfo list.  One or the other must accept each given clause!
 *
 * NB: Formerly, we made deep(!) copies of each input RestrictInfo to pass
 * up to the join relation.  I believe this is no longer necessary, because
 * RestrictInfo nodes are no longer context-dependent.  Instead, just include
 * the original nodes in the lists made for the join relation.
 */
static List *
build_joinrel_restrictlist(PlannerInfo *root,
               RelOptInfo *joinrel,
               RelOptInfo *outer_rel,
               RelOptInfo *inner_rel,
               SpecialJoinInfo *sjinfo)
{
  List     *result;
  Relids    both_input_relids;

  both_input_relids = bms_union(outer_rel->relids, inner_rel->relids);

  /*
   * Collect all the clauses that syntactically belong at this level,
   * eliminating any duplicates (important since we will see many of the
   * same clauses arriving from both input relations).
   */
  result = subbuild_joinrel_restrictlist(root, joinrel, outer_rel,
                       both_input_relids, NIL);
  result = subbuild_joinrel_restrictlist(root, joinrel, inner_rel,
                       both_input_relids, result);

  /*
   * Add on any clauses derived from EquivalenceClasses.  These cannot be
   * redundant with the clauses in the joininfo lists, so don't bother
   * checking.
   */
  result = list_concat(result,
             generate_join_implied_equalities(root,
                              joinrel->relids,
                              outer_rel->relids,
                              inner_rel,
                              sjinfo));

  return result;
}

static void
build_joinrel_joinlist(RelOptInfo *joinrel,
             RelOptInfo *outer_rel,
             RelOptInfo *inner_rel)
{
  List     *result;

  /*
   * Collect all the clauses that syntactically belong above this level,
   * eliminating any duplicates (important since we will see many of the
   * same clauses arriving from both input relations).
   */
  result = subbuild_joinrel_joinlist(joinrel, outer_rel->joininfo, NIL);
  result = subbuild_joinrel_joinlist(joinrel, inner_rel->joininfo, result);

  joinrel->joininfo = result;
}

static List *
subbuild_joinrel_restrictlist(PlannerInfo *root,
                RelOptInfo *joinrel,
                RelOptInfo *input_rel,
                Relids both_input_relids,
                List *new_restrictlist)
{
  ListCell   *l;

  foreach(l, input_rel->joininfo)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);

    if (bms_is_subset(rinfo->required_relids, joinrel->relids))
    {
      /*
       * This clause should become a restriction clause for the joinrel,
       * since it refers to no outside rels.  However, if it's a clone
       * clause then it might be too late to evaluate it, so we have to
       * check.  (If it is too late, just ignore the clause, taking it
       * on faith that another clone was or will be selected.)  Clone
       * clauses should always be outer-join clauses, so we compare
       * against both_input_relids.
       */
      if (rinfo->has_clone || rinfo->is_clone)
      {
        Assert(!RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids));
        if (!bms_is_subset(rinfo->required_relids, both_input_relids))
          continue;
        if (bms_overlap(rinfo->incompatible_relids, both_input_relids))
          continue;
      }
      else
      {
        /*
         * For non-clone clauses, we just Assert it's OK.  These might
         * be either join or filter clauses; if it's a join clause
         * then it should not refer to the current join's output.
         * (There is little point in checking incompatible_relids,
         * because it'll be NULL.)
         */
        Assert(RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids) ||
             bms_is_subset(rinfo->required_relids,
                   both_input_relids));
      }

      /*
       * OK, so add it to the list, being careful to eliminate
       * duplicates.  (Since RestrictInfo nodes in different joinlists
       * will have been multiply-linked rather than copied, pointer
       * equality should be a sufficient test.)
       */
      new_restrictlist = list_append_unique_ptr(new_restrictlist, rinfo);
    }
    else
    {
      /*
       * This clause is still a join clause at this level, so we ignore
       * it in this routine.
       */
    }
  }

  return new_restrictlist;
}

static List *
subbuild_joinrel_joinlist(RelOptInfo *joinrel,
              List *joininfo_list,
              List *new_joininfo)
{
  ListCell   *l;

  /* Expected to be called only for join between parent relations. */
  Assert(joinrel->reloptkind == RELOPT_JOINREL);

  foreach(l, joininfo_list)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);

    if (bms_is_subset(rinfo->required_relids, joinrel->relids))
    {
      /*
       * This clause becomes a restriction clause for the joinrel, since
       * it refers to no outside rels.  So we can ignore it in this
       * routine.
       */
    }
    else
    {
      /*
       * This clause is still a join clause at this level, so add it to
       * the new joininfo list, being careful to eliminate duplicates.
       * (Since RestrictInfo nodes in different joinlists will have been
       * multiply-linked rather than copied, pointer equality should be
       * a sufficient test.)
       */
      new_joininfo = list_append_unique_ptr(new_joininfo, rinfo);
    }
  }

  return new_joininfo;
}


/*
 * fetch_upper_rel
 *    Build a RelOptInfo describing some post-scan/join query processing,
 *    or return a pre-existing one if somebody already built it.
 *
 * An "upper" relation is identified by an UpperRelationKind and a Relids set.
 * The meaning of the Relids set is not specified here, and very likely will
 * vary for different relation kinds.
 *
 * Most of the fields in an upper-level RelOptInfo are not used and are not
 * set here (though makeNode should ensure they're zeroes).  We basically only
 * care about fields that are of interest to add_path() and set_cheapest().
 */
RelOptInfo *
fetch_upper_rel(PlannerInfo *root, UpperRelationKind kind, Relids relids)
{
  RelOptInfo *upperrel;
  ListCell   *lc;

  /*
   * For the moment, our indexing data structure is just a List for each
   * relation kind.  If we ever get so many of one kind that this stops
   * working well, we can improve it.  No code outside this function should
   * assume anything about how to find a particular upperrel.
   */

  /* If we already made this upperrel for the query, return it */
  foreach(lc, root->upper_rels[kind])
  {
    upperrel = (RelOptInfo *) lfirst(lc);

    if (bms_equal(upperrel->relids, relids))
      return upperrel;
  }

  upperrel = makeNode(RelOptInfo);
  upperrel->reloptkind = RELOPT_UPPER_REL;
  upperrel->relids = bms_copy(relids);

  /* cheap startup cost is interesting iff not all tuples to be retrieved */
  upperrel->consider_startup = (root->tuple_fraction > 0);
  upperrel->consider_param_startup = false;
  upperrel->consider_parallel = false;  /* might get changed later */
  upperrel->reltarget = create_empty_pathtarget();
  upperrel->pathlist = NIL;
  upperrel->cheapest_startup_path = NULL;
  upperrel->cheapest_total_path = NULL;
  upperrel->cheapest_unique_path = NULL;
  upperrel->cheapest_parameterized_paths = NIL;

  root->upper_rels[kind] = lappend(root->upper_rels[kind], upperrel);

  return upperrel;
}


/*
 * find_childrel_parents
 *    Compute the set of parent relids of an appendrel child rel.
 *
 * Since appendrels can be nested, a child could have multiple levels of
 * appendrel ancestors.  This function computes a Relids set of all the
 * parent relation IDs.
 */
Relids
find_childrel_parents(PlannerInfo *root, RelOptInfo *rel)
{
  Relids    result = NULL;

  Assert(rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
  Assert(rel->relid > 0 && rel->relid < root->simple_rel_array_size);

  do
  {
    AppendRelInfo *appinfo = root->append_rel_array[rel->relid];
    Index   prelid = appinfo->parent_relid;

    result = bms_add_member(result, prelid);

    /* traverse up to the parent rel, loop if it's also a child rel */
    rel = find_base_rel(root, prelid);
  } while (rel->reloptkind == RELOPT_OTHER_MEMBER_REL);

  Assert(rel->reloptkind == RELOPT_BASEREL);

  return result;
}


/*
 * get_baserel_parampathinfo
 *    Get the ParamPathInfo for a parameterized path for a base relation,
 *    constructing one if we don't have one already.
 *
 * This centralizes estimating the rowcounts for parameterized paths.
 * We need to cache those to be sure we use the same rowcount for all paths
 * of the same parameterization for a given rel.  This is also a convenient
 * place to determine which movable join clauses the parameterized path will
 * be responsible for evaluating.
 */
ParamPathInfo *
get_baserel_parampathinfo(PlannerInfo *root, RelOptInfo *baserel,
              Relids required_outer)
{
  ParamPathInfo *ppi;
  Relids    joinrelids;
  List     *pclauses;
  List     *eqclauses;
  Bitmapset  *pserials;
  double    rows;
  ListCell   *lc;

  /* If rel has LATERAL refs, every path for it should account for them */
  Assert(bms_is_subset(baserel->lateral_relids, required_outer));

  /* Unparameterized paths have no ParamPathInfo */
  if (bms_is_empty(required_outer))
    return NULL;

  Assert(!bms_overlap(baserel->relids, required_outer));

  /* If we already have a PPI for this parameterization, just return it */
  if ((ppi = find_param_path_info(baserel, required_outer)))
    return ppi;

  /*
   * Identify all joinclauses that are movable to this base rel given this
   * parameterization.
   */
  joinrelids = bms_union(baserel->relids, required_outer);
  pclauses = NIL;
  foreach(lc, baserel->joininfo)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

    if (join_clause_is_movable_into(rinfo,
                    baserel->relids,
                    joinrelids))
      pclauses = lappend(pclauses, rinfo);
  }

  /*
   * Add in joinclauses generated by EquivalenceClasses, too.  (These
   * necessarily satisfy join_clause_is_movable_into; but in assert-enabled
   * builds, let's verify that.)
   */
  eqclauses = generate_join_implied_equalities(root,
                         joinrelids,
                         required_outer,
                         baserel,
                         NULL);
#ifdef USE_ASSERT_CHECKING
  foreach(lc, eqclauses)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

    Assert(join_clause_is_movable_into(rinfo,
                       baserel->relids,
                       joinrelids));
  }
#endif
  pclauses = list_concat(pclauses, eqclauses);

  /* Compute set of serial numbers of the enforced clauses */
  pserials = NULL;
  foreach(lc, pclauses)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

    pserials = bms_add_member(pserials, rinfo->rinfo_serial);
  }

  /* Estimate the number of rows returned by the parameterized scan */
  rows = get_parameterized_baserel_size(root, baserel, pclauses);

  /* And now we can build the ParamPathInfo */
  ppi = makeNode(ParamPathInfo);
  ppi->ppi_req_outer = required_outer;
  ppi->ppi_rows = rows;
  ppi->ppi_clauses = pclauses;
  ppi->ppi_serials = pserials;
  baserel->ppilist = lappend(baserel->ppilist, ppi);

  return ppi;
}

/*
 * get_joinrel_parampathinfo
 *    Get the ParamPathInfo for a parameterized path for a join relation,
 *    constructing one if we don't have one already.
 *
 * This centralizes estimating the rowcounts for parameterized paths.
 * We need to cache those to be sure we use the same rowcount for all paths
 * of the same parameterization for a given rel.  This is also a convenient
 * place to determine which movable join clauses the parameterized path will
 * be responsible for evaluating.
 *
 * outer_path and inner_path are a pair of input paths that can be used to
 * construct the join, and restrict_clauses is the list of regular join
 * clauses (including clauses derived from EquivalenceClasses) that must be
 * applied at the join node when using these inputs.
 *
 * Unlike the situation for base rels, the set of movable join clauses to be
 * enforced at a join varies with the selected pair of input paths, so we
 * must calculate that and pass it back, even if we already have a matching
 * ParamPathInfo.  We handle this by adding any clauses moved down to this
 * join to *restrict_clauses, which is an in/out parameter.  (The addition
 * is done in such a way as to not modify the passed-in List structure.)
 *
 * Note: when considering a nestloop join, the caller must have removed from
 * restrict_clauses any movable clauses that are themselves scheduled to be
 * pushed into the right-hand path.  We do not do that here since it's
 * unnecessary for other join types.
 */
ParamPathInfo *
get_joinrel_parampathinfo(PlannerInfo *root, RelOptInfo *joinrel,
              Path *outer_path,
              Path *inner_path,
              SpecialJoinInfo *sjinfo,
              Relids required_outer,
              List **restrict_clauses)
{
  ParamPathInfo *ppi;
  Relids    join_and_req;
  Relids    outer_and_req;
  Relids    inner_and_req;
  List     *pclauses;
  List     *eclauses;
  List     *dropped_ecs;
  double    rows;
  ListCell   *lc;

  /* If rel has LATERAL refs, every path for it should account for them */
  Assert(bms_is_subset(joinrel->lateral_relids, required_outer));

  /* Unparameterized paths have no ParamPathInfo or extra join clauses */
  if (bms_is_empty(required_outer))
    return NULL;

  Assert(!bms_overlap(joinrel->relids, required_outer));

  /*
   * Identify all joinclauses that are movable to this join rel given this
   * parameterization.  These are the clauses that are movable into this
   * join, but not movable into either input path.  Treat an unparameterized
   * input path as not accepting parameterized clauses (because it won't,
   * per the shortcut exit above), even though the joinclause movement rules
   * might allow the same clauses to be moved into a parameterized path for
   * that rel.
   */
  join_and_req = bms_union(joinrel->relids, required_outer);
  if (outer_path->param_info)
    outer_and_req = bms_union(outer_path->parent->relids,
                  PATH_REQ_OUTER(outer_path));
  else
    outer_and_req = NULL; /* outer path does not accept parameters */
  if (inner_path->param_info)
    inner_and_req = bms_union(inner_path->parent->relids,
                  PATH_REQ_OUTER(inner_path));
  else
    inner_and_req = NULL; /* inner path does not accept parameters */

  pclauses = NIL;
  foreach(lc, joinrel->joininfo)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

    if (join_clause_is_movable_into(rinfo,
                    joinrel->relids,
                    join_and_req) &&
      !join_clause_is_movable_into(rinfo,
                     outer_path->parent->relids,
                     outer_and_req) &&
      !join_clause_is_movable_into(rinfo,
                     inner_path->parent->relids,
                     inner_and_req))
      pclauses = lappend(pclauses, rinfo);
  }

  /* Consider joinclauses generated by EquivalenceClasses, too */
  eclauses = generate_join_implied_equalities(root,
                        join_and_req,
                        required_outer,
                        joinrel,
                        NULL);
  /* We only want ones that aren't movable to lower levels */
  dropped_ecs = NIL;
  foreach(lc, eclauses)
  {
    RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

    Assert(join_clause_is_movable_into(rinfo,
                       joinrel->relids,
                       join_and_req));
    if (join_clause_is_movable_into(rinfo,
                    outer_path->parent->relids,
                    outer_and_req))
      continue;     /* drop if movable into LHS */
    if (join_clause_is_movable_into(rinfo,
                    inner_path->parent->relids,
                    inner_and_req))
    {
      /* drop if movable into RHS, but remember EC for use below */
      Assert(rinfo->left_ec == rinfo->right_ec);
      dropped_ecs = lappend(dropped_ecs, rinfo->left_ec);
      continue;
    }
    pclauses = lappend(pclauses, rinfo);
  }

  /*
   * EquivalenceClasses are harder to deal with than we could wish, because
   * of the fact that a given EC can generate different clauses depending on
   * context.  Suppose we have an EC {X.X, Y.Y, Z.Z} where X and Y are the
   * LHS and RHS of the current join and Z is in required_outer, and further
   * suppose that the inner_path is parameterized by both X and Z.  The code
   * above will have produced either Z.Z = X.X or Z.Z = Y.Y from that EC,
   * and in the latter case will have discarded it as being movable into the
   * RHS.  However, the EC machinery might have produced either Y.Y = X.X or
   * Y.Y = Z.Z as the EC enforcement clause within the inner_path; it will
   * not have produced both, and we can't readily tell from here which one
   * it did pick.  If we add no clause to this join, we'll end up with
   * insufficient enforcement of the EC; either Z.Z or X.X will fail to be
   * constrained to be equal to the other members of the EC.  (When we come
   * to join Z to this X/Y path, we will certainly drop whichever EC clause
   * is generated at that join, so this omission won't get fixed later.)
   *
   * To handle this, for each EC we discarded such a clause from, try to
   * generate a clause connecting the required_outer rels to the join's LHS
   * ("Z.Z = X.X" in the terms of the above example).  If successful, and if
   * the clause can't be moved to the LHS, add it to the current join's
   * restriction clauses.  (If an EC cannot generate such a clause then it
   * has nothing that needs to be enforced here, while if the clause can be
   * moved into the LHS then it should have been enforced within that path.)
   *
   * Note that we don't need similar processing for ECs whose clause was
   * considered to be movable into the LHS, because the LHS can't refer to
   * the RHS so there is no comparable ambiguity about what it might
   * actually be enforcing internally.
   */
  if (dropped_ecs)
  {
    Relids    real_outer_and_req;

    real_outer_and_req = bms_union(outer_path->parent->relids,
                     required_outer);
    eclauses =
      generate_join_implied_equalities_for_ecs(root,
                           dropped_ecs,
                           real_outer_and_req,
                           required_outer,
                           outer_path->parent);
    foreach(lc, eclauses)
    {
      RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

      Assert(join_clause_is_movable_into(rinfo,
                         outer_path->parent->relids,
                         real_outer_and_req));
      if (!join_clause_is_movable_into(rinfo,
                       outer_path->parent->relids,
                       outer_and_req))
        pclauses = lappend(pclauses, rinfo);
    }
  }

  /*
   * Now, attach the identified moved-down clauses to the caller's
   * restrict_clauses list.  By using list_concat in this order, we leave
   * the original list structure of restrict_clauses undamaged.
   */
  *restrict_clauses = list_concat(pclauses, *restrict_clauses);

  /* If we already have a PPI for this parameterization, just return it */
  if ((ppi = find_param_path_info(joinrel, required_outer)))
    return ppi;

  /* Estimate the number of rows returned by the parameterized join */
  rows = get_parameterized_joinrel_size(root, joinrel,
                      outer_path,
                      inner_path,
                      sjinfo,
                      *restrict_clauses);

  /*
   * And now we can build the ParamPathInfo.  No point in saving the
   * input-pair-dependent clause list, though.
   *
   * Note: in GEQO mode, we'll be called in a temporary memory context, but
   * the joinrel structure is there too, so no problem.
   */
  ppi = makeNode(ParamPathInfo);
  ppi->ppi_req_outer = required_outer;
  ppi->ppi_rows = rows;
  ppi->ppi_clauses = NIL;
  ppi->ppi_serials = NULL;
  joinrel->ppilist = lappend(joinrel->ppilist, ppi);

  return ppi;
}

/*
 * get_appendrel_parampathinfo
 *    Get the ParamPathInfo for a parameterized path for an append relation.
 *
 * For an append relation, the rowcount estimate will just be the sum of
 * the estimates for its children.  However, we still need a ParamPathInfo
 * to flag the fact that the path requires parameters.  So this just creates
 * a suitable struct with zero ppi_rows (and no ppi_clauses either, since
 * the Append node isn't responsible for checking quals).
 */
ParamPathInfo *
get_appendrel_parampathinfo(RelOptInfo *appendrel, Relids required_outer)
{
  ParamPathInfo *ppi;

  /* If rel has LATERAL refs, every path for it should account for them */
  Assert(bms_is_subset(appendrel->lateral_relids, required_outer));

  /* Unparameterized paths have no ParamPathInfo */
  if (bms_is_empty(required_outer))
    return NULL;

  Assert(!bms_overlap(appendrel->relids, required_outer));

  /* If we already have a PPI for this parameterization, just return it */
  if ((ppi = find_param_path_info(appendrel, required_outer)))
    return ppi;

  /* Else build the ParamPathInfo */
  ppi = makeNode(ParamPathInfo);
  ppi->ppi_req_outer = required_outer;
  ppi->ppi_rows = 0;
  ppi->ppi_clauses = NIL;
  ppi->ppi_serials = NULL;
  appendrel->ppilist = lappend(appendrel->ppilist, ppi);

  return ppi;
}

/*
 * Returns a ParamPathInfo for the parameterization given by required_outer, if
 * already available in the given rel. Returns NULL otherwise.
 */
ParamPathInfo *
find_param_path_info(RelOptInfo *rel, Relids required_outer)
{
  ListCell   *lc;

  foreach(lc, rel->ppilist)
  {
    ParamPathInfo *ppi = (ParamPathInfo *) lfirst(lc);

    if (bms_equal(ppi->ppi_req_outer, required_outer))
      return ppi;
  }

  return NULL;
}

/*
 * get_param_path_clause_serials
 *    Given a parameterized Path, return the set of pushed-down clauses
 *    (identified by rinfo_serial numbers) enforced within the Path.
 */
Bitmapset *
get_param_path_clause_serials(Path *path)
{
  if (path->param_info == NULL)
    return NULL;     /* not parameterized */

  /*
   * We don't currently support parameterized MergeAppend paths, as
   * explained in the comments for generate_orderedappend_paths.
   */
  Assert(!IsA(path, MergeAppendPath));

  if (IsA(path, NestPath) ||
    IsA(path, MergePath) ||
    IsA(path, HashPath))
  {
    /*
     * For a join path, combine clauses enforced within either input path
     * with those enforced as joinrestrictinfo in this path.  Note that
     * joinrestrictinfo may include some non-pushed-down clauses, but for
     * current purposes it's okay if we include those in the result. (To
     * be more careful, we could check for clause_relids overlapping the
     * path parameterization, but it's not worth the cycles for now.)
     */
    JoinPath   *jpath = (JoinPath *) path;
    Bitmapset  *pserials;
    ListCell   *lc;

    pserials = NULL;
    pserials = bms_add_members(pserials,
                   get_param_path_clause_serials(jpath->outerjoinpath));
    pserials = bms_add_members(pserials,
                   get_param_path_clause_serials(jpath->innerjoinpath));
    foreach(lc, jpath->joinrestrictinfo)
    {
      RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);

      pserials = bms_add_member(pserials, rinfo->rinfo_serial);
    }
    return pserials;
  }
  else if (IsA(path, AppendPath))
  {
    /*
     * For an appendrel, take the intersection of the sets of clauses
     * enforced in each input path.
     */
    AppendPath *apath = (AppendPath *) path;
    Bitmapset  *pserials;
    ListCell   *lc;

    pserials = NULL;
    foreach(lc, apath->subpaths)
    {
      Path     *subpath = (Path *) lfirst(lc);
      Bitmapset  *subserials;

      subserials = get_param_path_clause_serials(subpath);
      if (lc == list_head(apath->subpaths))
        pserials = bms_copy(subserials);
      else
        pserials = bms_int_members(pserials, subserials);
    }
    return pserials;
  }
  else
  {
    /*
     * Otherwise, it's a baserel path and we can use the
     * previously-computed set of serial numbers.
     */
    return path->param_info->ppi_serials;
  }
}

/*
 * build_joinrel_partition_info
 *    Checks if the two relations being joined can use partitionwise join
 *    and if yes, initialize partitioning information of the resulting
 *    partitioned join relation.
 */
static void
build_joinrel_partition_info(PlannerInfo *root,
               RelOptInfo *joinrel, RelOptInfo *outer_rel,
               RelOptInfo *inner_rel, SpecialJoinInfo *sjinfo,
               List *restrictlist)
{
  PartitionScheme part_scheme;

  /* Nothing to do if partitionwise join technique is disabled. */
  if (!enable_partitionwise_join)
  {
    Assert(!IS_PARTITIONED_REL(joinrel));
    return;
  }

  /*
   * We can only consider this join as an input to further partitionwise
   * joins if (a) the input relations are partitioned and have
   * consider_partitionwise_join=true, (b) the partition schemes match, and
   * (c) we can identify an equi-join between the partition keys.  Note that
   * if it were possible for have_partkey_equi_join to return different
   * answers for the same joinrel depending on which join ordering we try
   * first, this logic would break.  That shouldn't happen, though, because
   * of the way the query planner deduces implied equalities and reorders
   * the joins.  Please see optimizer/README for details.
   */
  if (outer_rel->part_scheme == NULL || inner_rel->part_scheme == NULL ||
    !outer_rel->consider_partitionwise_join ||
    !inner_rel->consider_partitionwise_join ||
    outer_rel->part_scheme != inner_rel->part_scheme ||
    !have_partkey_equi_join(root, joinrel, outer_rel, inner_rel,
                sjinfo->jointype, restrictlist))
  {
    Assert(!IS_PARTITIONED_REL(joinrel));
    return;
  }

  part_scheme = outer_rel->part_scheme;

  /*
   * This function will be called only once for each joinrel, hence it
   * should not have partitioning fields filled yet.
   */
  Assert(!joinrel->part_scheme && !joinrel->partexprs &&
       !joinrel->nullable_partexprs && !joinrel->part_rels &&
       !joinrel->boundinfo);

  /*
   * If the join relation is partitioned, it uses the same partitioning
   * scheme as the joining relations.
   *
   * Note: we calculate the partition bounds, number of partitions, and
   * child-join relations of the join relation in try_partitionwise_join().
   */
  joinrel->part_scheme = part_scheme;
  set_joinrel_partition_key_exprs(joinrel, outer_rel, inner_rel,
                  sjinfo->jointype);

  /*
   * Set the consider_partitionwise_join flag.
   */
  Assert(outer_rel->consider_partitionwise_join);
  Assert(inner_rel->consider_partitionwise_join);
  joinrel->consider_partitionwise_join = true;
}

/*
 * have_partkey_equi_join
 *
 * Returns true if there exist equi-join conditions involving pairs
 * of matching partition keys of the relations being joined for all
 * partition keys.
 */
static bool
have_partkey_equi_join(PlannerInfo *root, RelOptInfo *joinrel,
             RelOptInfo *rel1, RelOptInfo *rel2,
             JoinType jointype, List *restrictlist)
{
  PartitionScheme part_scheme = rel1->part_scheme;
  bool    pk_known_equal[PARTITION_MAX_KEYS];
  int     num_equal_pks;
  ListCell   *lc;

  /*
   * This function must only be called when the joined relations have same
   * partitioning scheme.
   */
  Assert(rel1->part_scheme == rel2->part_scheme);
  Assert(part_scheme);

  /* We use a bool array to track which partkey columns are known equal */
  memset(pk_known_equal, 0, sizeof(pk_known_equal));
  /* ... as well as a count of how many are known equal */
  num_equal_pks = 0;

  /* First, look through the join's restriction clauses */
  foreach(lc, restrictlist)
  {
    RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
    OpExpr     *opexpr;
    Expr     *expr1;
    Expr     *expr2;
    bool    strict_op;
    int     ipk1;
    int     ipk2;

    /* If processing an outer join, only use its own join clauses. */
    if (IS_OUTER_JOIN(jointype) &&
      RINFO_IS_PUSHED_DOWN(rinfo, joinrel->relids))
      continue;

    /* Skip clauses which can not be used for a join. */
    if (!rinfo->can_join)
      continue;

    /* Skip clauses which are not equality conditions. */
    if (!rinfo->mergeopfamilies && !OidIsValid(rinfo->hashjoinoperator))
      continue;

    /* Should be OK to assume it's an OpExpr. */
    opexpr = castNode(OpExpr, rinfo->clause);

    /* Match the operands to the relation. */
    if (bms_is_subset(rinfo->left_relids, rel1->relids) &&
      bms_is_subset(rinfo->right_relids, rel2->relids))
    {
      expr1 = linitial(opexpr->args);
      expr2 = lsecond(opexpr->args);
    }
    else if (bms_is_subset(rinfo->left_relids, rel2->relids) &&
         bms_is_subset(rinfo->right_relids, rel1->relids))
    {
      expr1 = lsecond(opexpr->args);
      expr2 = linitial(opexpr->args);
    }
    else
      continue;

    /*
     * Now we need to know whether the join operator is strict; see
     * comments in pathnodes.h.
     */
    strict_op = op_strict(opexpr->opno);

    /*
     * Vars appearing in the relation's partition keys will not have any
     * varnullingrels, but those in expr1 and expr2 will if we're above
     * outer joins that could null the respective rels.  It's okay to
     * match anyway, if the join operator is strict.
     */
    if (strict_op)
    {
      if (bms_overlap(rel1->relids, root->outer_join_rels))
        expr1 = (Expr *) remove_nulling_relids((Node *) expr1,
                             root->outer_join_rels,
                             NULL);
      if (bms_overlap(rel2->relids, root->outer_join_rels))
        expr2 = (Expr *) remove_nulling_relids((Node *) expr2,
                             root->outer_join_rels,
                             NULL);
    }

    /*
     * Only clauses referencing the partition keys are useful for
     * partitionwise join.
     */
    ipk1 = match_expr_to_partition_keys(expr1, rel1, strict_op);
    if (ipk1 < 0)
      continue;
    ipk2 = match_expr_to_partition_keys(expr2, rel2, strict_op);
    if (ipk2 < 0)
      continue;

    /*
     * If the clause refers to keys at different ordinal positions, it can
     * not be used for partitionwise join.
     */
    if (ipk1 != ipk2)
      continue;

    /* Ignore clause if we already proved these keys equal. */
    if (pk_known_equal[ipk1])
      continue;

    /* Reject if the partition key collation differs from the clause's. */
    if (rel1->part_scheme->partcollation[ipk1] != opexpr->inputcollid)
      return false;

    /*
     * The clause allows partitionwise join only if it uses the same
     * operator family as that specified by the partition key.
     */
    if (part_scheme->strategy == PARTITION_STRATEGY_HASH)
    {
      if (!OidIsValid(rinfo->hashjoinoperator) ||
        !op_in_opfamily(rinfo->hashjoinoperator,
                part_scheme->partopfamily[ipk1]))
        continue;
    }
    else if (!list_member_oid(rinfo->mergeopfamilies,
                  part_scheme->partopfamily[ipk1]))
      continue;

    /* Mark the partition key as having an equi-join clause. */
    pk_known_equal[ipk1] = true;

    /* We can stop examining clauses once we prove all keys equal. */
    if (++num_equal_pks == part_scheme->partnatts)
      return true;
  }

  /*
   * Also check to see if any keys are known equal by equivclass.c.  In most
   * cases there would have been a join restriction clause generated from
   * any EC that had such knowledge, but there might be no such clause, or
   * it might happen to constrain other members of the ECs than the ones we
   * are looking for.
   */
  for (int ipk = 0; ipk < part_scheme->partnatts; ipk++)
  {
    Oid     btree_opfamily;

    /* Ignore if we already proved these keys equal. */
    if (pk_known_equal[ipk])
      continue;

    /*
     * We need a btree opfamily to ask equivclass.c about.  If the
     * partopfamily is a hash opfamily, look up its equality operator, and
     * select some btree opfamily that that operator is part of.  (Any
     * such opfamily should be good enough, since equivclass.c will track
     * multiple opfamilies as appropriate.)
     */
    if (part_scheme->strategy == PARTITION_STRATEGY_HASH)
    {
      Oid     eq_op;
      List     *eq_opfamilies;

      eq_op = get_opfamily_member(part_scheme->partopfamily[ipk],
                    part_scheme->partopcintype[ipk],
                    part_scheme->partopcintype[ipk],
                    HTEqualStrategyNumber);
      if (!OidIsValid(eq_op))
        break;     /* we're not going to succeed */
      eq_opfamilies = get_mergejoin_opfamilies(eq_op);
      if (eq_opfamilies == NIL)
        break;     /* we're not going to succeed */
      btree_opfamily = linitial_oid(eq_opfamilies);
    }
    else
      btree_opfamily = part_scheme->partopfamily[ipk];

    /*
     * We consider only non-nullable partition keys here; nullable ones
     * would not be treated as part of the same equivalence classes as
     * non-nullable ones.
     */
    foreach(lc, rel1->partexprs[ipk])
    {
      Node     *expr1 = (Node *) lfirst(lc);
      ListCell   *lc2;
      Oid     partcoll1 = rel1->part_scheme->partcollation[ipk];
      Oid     exprcoll1 = exprCollation(expr1);

      foreach(lc2, rel2->partexprs[ipk])
      {
        Node     *expr2 = (Node *) lfirst(lc2);

        if (exprs_known_equal(root, expr1, expr2, btree_opfamily))
        {
          /*
           * Ensure that the collation of the expression matches
           * that of the partition key. Checking just one collation
           * (partcoll1 and exprcoll1) suffices because partcoll1
           * and partcoll2, as well as exprcoll1 and exprcoll2,
           * should be identical. This holds because both rel1 and
           * rel2 use the same PartitionScheme and expr1 and expr2
           * are equal.
           */
          if (partcoll1 == exprcoll1)
          {
            Oid     partcoll2 PG_USED_FOR_ASSERTS_ONLY =
              rel2->part_scheme->partcollation[ipk];
            Oid     exprcoll2 PG_USED_FOR_ASSERTS_ONLY =
              exprCollation(expr2);

            Assert(partcoll2 == exprcoll2);
            pk_known_equal[ipk] = true;
            break;
          }
        }
      }
      if (pk_known_equal[ipk])
        break;
    }

    if (pk_known_equal[ipk])
    {
      /* We can stop examining keys once we prove all keys equal. */
      if (++num_equal_pks == part_scheme->partnatts)
        return true;
    }
    else
      break;       /* no chance to succeed, give up */
  }

  return false;
}

/*
 * match_expr_to_partition_keys
 *
 * Tries to match an expression to one of the nullable or non-nullable
 * partition keys of "rel".  Returns the matched key's ordinal position,
 * or -1 if the expression could not be matched to any of the keys.
 *
 * strict_op must be true if the expression will be compared with the
 * partition key using a strict operator.  This allows us to consider
 * nullable as well as nonnullable partition keys.
 */
static int
match_expr_to_partition_keys(Expr *expr, RelOptInfo *rel, bool strict_op)
{
  int     cnt;

  /* This function should be called only for partitioned relations. */
  Assert(rel->part_scheme);
  Assert(rel->partexprs);
  Assert(rel->nullable_partexprs);

  /* Remove any relabel decorations. */
  while (IsA(expr, RelabelType))
    expr = (Expr *) (castNode(RelabelType, expr))->arg;

  for (cnt = 0; cnt < rel->part_scheme->partnatts; cnt++)
  {
    ListCell   *lc;

    /* We can always match to the non-nullable partition keys. */
    foreach(lc, rel->partexprs[cnt])
    {
      if (equal(lfirst(lc), expr))
        return cnt;
    }

    if (!strict_op)
      continue;

    /*
     * If it's a strict join operator then a NULL partition key on one
     * side will not join to any partition key on the other side, and in
     * particular such a row can't join to a row from a different
     * partition on the other side.  So, it's okay to search the nullable
     * partition keys as well.
     */
    foreach(lc, rel->nullable_partexprs[cnt])
    {
      if (equal(lfirst(lc), expr))
        return cnt;
    }
  }

  return -1;
}

/*
 * set_joinrel_partition_key_exprs
 *    Initialize partition key expressions for a partitioned joinrel.
 */
static void
set_joinrel_partition_key_exprs(RelOptInfo *joinrel,
                RelOptInfo *outer_rel, RelOptInfo *inner_rel,
                JoinType jointype)
{
  PartitionScheme part_scheme = joinrel->part_scheme;
  int     partnatts = part_scheme->partnatts;

  joinrel->partexprs = (List **) palloc0(sizeof(List *) * partnatts);
  joinrel->nullable_partexprs =
    (List **) palloc0(sizeof(List *) * partnatts);

  /*
   * The joinrel's partition expressions are the same as those of the input
   * rels, but we must properly classify them as nullable or not in the
   * joinrel's output.  (Also, we add some more partition expressions if
   * it's a FULL JOIN.)
   */
  for (int cnt = 0; cnt < partnatts; cnt++)
  {
    /* mark these const to enforce that we copy them properly */
    const List *outer_expr = outer_rel->partexprs[cnt];
    const List *outer_null_expr = outer_rel->nullable_partexprs[cnt];
    const List *inner_expr = inner_rel->partexprs[cnt];
    const List *inner_null_expr = inner_rel->nullable_partexprs[cnt];
    List     *partexpr = NIL;
    List     *nullable_partexpr = NIL;
    ListCell   *lc;

    switch (jointype)
    {
        /*
         * A join relation resulting from an INNER join may be
         * regarded as partitioned by either of the inner and outer
         * relation keys.  For example, A INNER JOIN B ON A.a = B.b
         * can be regarded as partitioned on either A.a or B.b.  So we
         * add both keys to the joinrel's partexpr lists.  However,
         * anything that was already nullable still has to be treated
         * as nullable.
         */
      case JOIN_INNER:
        partexpr = list_concat_copy(outer_expr, inner_expr);
        nullable_partexpr = list_concat_copy(outer_null_expr,
                           inner_null_expr);
        break;

        /*
         * A join relation resulting from a SEMI or ANTI join may be
         * regarded as partitioned by the outer relation keys.  The
         * inner relation's keys are no longer interesting; since they
         * aren't visible in the join output, nothing could join to
         * them.
         */
      case JOIN_SEMI:
      case JOIN_ANTI:
        partexpr = list_copy(outer_expr);
        nullable_partexpr = list_copy(outer_null_expr);
        break;

        /*
         * A join relation resulting from a LEFT OUTER JOIN likewise
         * may be regarded as partitioned on the (non-nullable) outer
         * relation keys.  The inner (nullable) relation keys are okay
         * as partition keys for further joins as long as they involve
         * strict join operators.
         */
      case JOIN_LEFT:
        partexpr = list_copy(outer_expr);
        nullable_partexpr = list_concat_copy(inner_expr,
                           outer_null_expr);
        nullable_partexpr = list_concat(nullable_partexpr,
                        inner_null_expr);
        break;

        /*
         * For FULL OUTER JOINs, both relations are nullable, so the
         * resulting join relation may be regarded as partitioned on
         * either of inner and outer relation keys, but only for joins
         * that involve strict join operators.
         */
      case JOIN_FULL:
        nullable_partexpr = list_concat_copy(outer_expr,
                           inner_expr);
        nullable_partexpr = list_concat(nullable_partexpr,
                        outer_null_expr);
        nullable_partexpr = list_concat(nullable_partexpr,
                        inner_null_expr);

        /*
         * Also add CoalesceExprs corresponding to each possible
         * full-join output variable (that is, left side coalesced to
         * right side), so that we can match equijoin expressions
         * using those variables.  We really only need these for
         * columns merged by JOIN USING, and only with the pairs of
         * input items that correspond to the data structures that
         * parse analysis would build for such variables.  But it's
         * hard to tell which those are, so just make all the pairs.
         * Extra items in the nullable_partexprs list won't cause big
         * problems.  (It's possible that such items will get matched
         * to user-written COALESCEs, but it should still be valid to
         * partition on those, since they're going to be either the
         * partition column or NULL; it's the same argument as for
         * partitionwise nesting of any outer join.)  We assume no
         * type coercions are needed to make the coalesce expressions,
         * since columns of different types won't have gotten
         * classified as the same PartitionScheme.  Note that we
         * intentionally leave out the varnullingrels decoration that
         * would ordinarily appear on the Vars inside these
         * CoalesceExprs, because have_partkey_equi_join will strip
         * varnullingrels from the expressions it will compare to the
         * partexprs.
         */
        foreach(lc, list_concat_copy(outer_expr, outer_null_expr))
        {
          Node     *larg = (Node *) lfirst(lc);
          ListCell   *lc2;

          foreach(lc2, list_concat_copy(inner_expr, inner_null_expr))
          {
            Node     *rarg = (Node *) lfirst(lc2);
            CoalesceExpr *c = makeNode(CoalesceExpr);

            c->coalescetype = exprType(larg);
            c->coalescecollid = exprCollation(larg);
            c->args = list_make2(larg, rarg);
            c->location = -1;
            nullable_partexpr = lappend(nullable_partexpr, c);
          }
        }
        break;

      default:
        elog(ERROR, "unrecognized join type: %d", (int) jointype);
    }

    joinrel->partexprs[cnt] = partexpr;
    joinrel->nullable_partexprs[cnt] = nullable_partexpr;
  }
}

/*
 * build_child_join_reltarget
 *    Set up a child-join relation's reltarget from a parent-join relation.
 */
static void
build_child_join_reltarget(PlannerInfo *root,
               RelOptInfo *parentrel,
               RelOptInfo *childrel,
               int nappinfos,
               AppendRelInfo **appinfos)
{
  /* Build the targetlist */
  childrel->reltarget->exprs = (List *)
    adjust_appendrel_attrs(root,
                 (Node *) parentrel->reltarget->exprs,
                 nappinfos, appinfos);

  /* Set the cost and width fields */
  childrel->reltarget->cost.startup = parentrel->reltarget->cost.startup;
  childrel->reltarget->cost.per_tuple = parentrel->reltarget->cost.per_tuple;
  childrel->reltarget->width = parentrel->reltarget->width;
}

Coverage Report

Created: 2025-06-13 06:06